1. Field of the Invention
The present invention relates to an electronic chip component feeder, and more specifically relates to an electronic chip component feeder in which a plurality of feeding units respectively supply each of a plurality of kinds of chip components and are reciprocated (e.g., moved back and forth) in the course of a feeding operation.
2. Description of the Related Art
Most electronic components capable of being surface-mounted, such as capacitors, resistors and inductors, are chip-shaped (e.g., have a small box-like, cylindrical or other shapes). In order to mount such electronic components on a substrate, a chip mounter is used. An electronic chip component feeder is built into the chip mounter.
The electronic chip component feeder separately supplies a plurality of kinds of electronic chip components, respectively, through a plurality of feeding units disposed in parallel with each other. Each feeding unit has a hopper which accommodates and discharges a plurality of components of a specific kind. Further, each feeding unit has a guide path which guides the components discharged by the hopper in alignment to a predetermined dispensing location.
The plurality of feeding units can be arranged in an array, such as a linear array. The feeding units can be reciprocated (e.g., moved back and forth) in unison in an "array direction," e.g., in a direction defined by the arrangement of the feeding units in the array. By this reciprocating transfer, the dispensing location through which the components are dispensed can be transferred to a predefined fixed position. The components located at the dispensing location, which is made coincident with the fixed position, are removed one by one using a pick-up mechanism. The pick-up mechanism may comprise, for example, a sucking chuck which picks up and holds components by exerting a vacuum sucking force. The pick-up mechanism is controlled so as to repeatedly reciprocate (e.g., move back and forth) between the above-mentioned fixed position and a position at which a chip component is mounted during a mounting operation (referred to as the "mounting position").
As described above, the mounting operation of the chip components is achieved by repeated reciprocation of the pick-up mechanism between the fixed position and the mounting position. The plurality of feeding units must be transferred in a desired direction and over a desired distance to make the dispensing location of a particular feeding unit coincident with the predefined fixed position. This operation is performed repeatedly, so as to pick-up components in a desired order and mount desired kinds of components using the pick-up mechanism.
Accordingly, a feeding unit is generally moved and stopped several times in the course of mounting operations. Therefore, the chip components, accommodated in the hopper of the feeding unit, repeatedly collide with each other or with the hopper walls at every acceleration and deceleration of the unit (e.g., when the movement of the hopper starts and stops). Further, in order to speed up the mounting operation, the unit is moved quickly using rapid accelerations and decelerations (that is, movement starts and stops quickly). This can apply a substantial amount of mechanical shock to the electronic chip components during the above-described collisions.
Moreover, a huge number of electronic chip components, from several hundreds up to several millions for example, are accommodated in the hopper of each feeding unit during mounting operations. Depending on the requirements of a particular mounting operation, some components have a comparatively short stay in the hopper, while other components remain in the hopper for a relatively long time. For example, most of the components which are consumed in small quantities in the mounting process remain in the hopper for a relatively long time.
When the components remaining in the hopper for a long time undergo repeated collisions in the manner described above, the quality of the electronic chip components may degrade. For example, chipping and cracking of the electronic chip components may occur. Also, substantial discoloring of the outer surface or degradation in solderability of components having electrodes formed on the outer surface thereof may occur.
The mounting of defective electronic chip components to a substrate results in the production of substandard circuit boards. This, in turn, may require replacement of defective components, which reduces productivity.